Dell venue 11 pro 7139 battery keyboard

I wonder if anyone can help, I have a Dell Venue 11 Pro 7139, I bought a Dell tablet keyboard the one with the built in battery. The problem I have is the tablet doesn't see the keyboard, I've charged the keyboard until the charge light went off via the mini usb port on the keyboard. I'm pretty sure my tablet is all up to date using Dell Command updates. Any ideas?